In the sport of surfing, up until a few years ago, when a surfer was separated from his board in the surf, the surfer would remain about where he fell but the board would careen through the water under wave action until it reached the beach. This was undesirable for two obvious reasons, the first being the danger to bathers in the area which is considerable if the beach is crowded, and the second being the inconvenience to the surfer who would almost without fail have to swim the entire distance to the beach to recover his board.
The difficulties lead to the invention of the surfboard leash which connects the surfer's ankle to the board, making the surfer something like a sea anchor restraining the board when he falls off. Although leashes have become more sophisticated since the initial development, it is still quite common for them to age and eventually break, particularly if they include a length of soft elastic to avoid jolting the surfer when the board reaches the end of the leash.